Coating mineral aggregates



Patented Marf17, 19462 COATING MINERAL AGGREGATES Elton B. Tucker,Highland, Ind., and Henry M. Grubb, Chicago, 11]., asslgnors to StandardOil p Indiana Chicago, 111., a corporation of No Drawing. ApplicationNovember 20, 1940,

, Serial'No.-366,382

18 Claims. (Cl. 106-273) V The'present invention relates to improvementsin coating mineral aggregates with oil or'bitiiminous material andparticularly to the use of addition agents to improve the adherence ofcracked bituminous materials or cracked oils to mineral aggregates inthe presence of water.

Oils and/or bituminous paving materials do not coatand adhere well tomineral aggregates unless the aggregate is substantially dry, and forthis reason in conventionalpavement or road construction practice it iscustomary to dry the mineral aggregate by suitable well-known methodssuch as by heating or air drying. Furthermore, water entering the roador pavement during service also may .have a detrimental' eifect, in thatit may displace the oil or bitumen from the surface of the aggregate andthus diminish the bonding effect of the bitumen on the mixture bydisrupting the bitumen-aggregate bond. This materially shortens the lifeof the road or pavement, requiring frequent repairs and is thereforehighly undesirable.

Mineral aggregates employed in road or pavement construction range incharacter from hydrophylic to hydrophobic. In general, siliceous andacidic mineral tend to be hydrophilic, and cal-. careous alkalineminerals tend to be hydrophobic. It has been observed that siliceousacidic minerals have a greater attraction for water than for oil orbitumens, and that it is difllcult to obtain, by-conventional methods,complete or satisfactory coating of such aggregates by oil or bitumenwhen water is present. Further, even though'satisfactory coating isobtained by using dry aggregate, the film of oil or bitumen tends to bedisplaced if water enters the pavement. While alkaline, calcareous,hydrophobic aggregates in general exhibit less tendency to stripping ofthe bitruninous film or coating by water than do hydrophilic aggregates,even when hydrophobic aggregates are used the oil or bitumen does notalways resist displacement from the aggregate surface by water.

It is an object of the present invention to provide an agent whichpromotes adherence of oilsand/or bituminous materials more especiallycracked oils and/or cracked bituminous materials to mineral aggregates,particularly hydrophilic siliceous aggregates, without the necessity ofdrying the same. Another object of the invention is to provide a meansof preventing or reducing the tendency toward stripping of these oil andbituminous materials from the mineral aggregate by water after the roador pavement or other structure 'is constructed. Other objects used alsodepends upon the composition, or char- I and advantages of the inventionwill become apparent as the description thereof proceeds.

We have discovered that the foregoing objects can be attained by addinginorganic halides, particularly metalloid halides to the oil orbituminous material. The halides which we employ are the halides of themetalloids of the fifth group of the periodic system and preferably thechloride and bromides 'of phosphorus, antimony, and

arsenic, specifically P013, P015, PBra, PBrs, SbCla, V

SbCfis, SbBr5, and ASCla, etc. While the specific activity of thesematerials varies to some extent, all of them are effective in promotingthe adherence-of oil. and bituminous materials to mineral aggregates.The metalloid trihalides, particularly phosphorous trichloride andantimony trichloride, are most effective in promoting the adherence. ofbituminous materials particularly cracked road oils and/or crackedasphalts, to mineral aggregates.

The amount of metalloid halide, for example PCla, to be used dependsupon several factors,

among which are the type of oil or bituminous material to be applied,the surface characteristics ofthe aggregate, and the area of theaggregatebitumen interface. For example, some road-oils are benefited byamounts of PC13 up to 1.0%, while others will be benefited by amounts upto 0.1%, but will not be further benefited by amounts of P013 greaterthan 0.1%. This appears to be a characteristic or property of thebituminous material which cannot be predicted by analysis or from otherproperties of the bituminous materials, and accordingly, as will beappreciated by those skilled in the art of compounding bituminousmaterials, must be determined by trial on the individual sample or typeof bituminous material. The amount of metalloid halide to be acteristicsof the aggregate surface. ,In general, siliceous aggregates are moreresponsive to the use of such'addition agents than are calcareous,alkaline aggregates. Accordingly, with aggregates which arepredominantly siliceous, larger amounts ofthe metalloid halide canadvantageously be added than with aggregates which are predominantlycalcareous. The area of the aggregate-bitumen interface also influencesthe amount to be used. It'will be understood by those skilled in the artthat as this area, which depends upon the particle size distribution,particle shape, and degree of surface roughness or smoothness of theaggregate, and upon the proportions of aggregate and bituminousmaterial, varies, the amount of metalloid halide which it is appreciatedthat these three factors are interdeaaregae i the benefits outlinedherein, the adherence of the pendent to some extent, and that thereforethe amount of metalloid halide which can most advantageously be usedmust be determined for the individual combination of bituminous materialand aggregate. In general we have found that the amount required toproduce the optimum effects is from 0.025% to about 5% or more, and

preferably from about 0.05 to 1%, based upon the oil orbitumen used.

The addition agents described herein can be added to the bituminousmaterial at about room temperature and the mixture employed immediately.Optionally, the addition agents can be added to the hot bituminousmaterial at an elevated temperature of about 150 F. to about 400 oradded to the mixture of bituminous material and mineral aggregateduring. preparation of the mixture, or incorporated in the aggregate,preferably immediately prior to addition of the bitumen.

It is known that the coating of mineral aggregates by oil or bitumen inthe presence of water can be effected, and the resistance of the coatingto stripping or displacement by water improved, by treating theaggregate with an aqueous solution of a polyvalent metal salt, andsubsequently applying thereto a small amount of a watersoluble soap of afatty acid. The. mechanism whereby the aggregate is made preferentiallywetted by the bituminous material and the latter Ltherefore made moreadherent to the aggregate,

is theoretically as follows: It is believed that one valence of theheavy metal ion is attached to the mineral and another valence reactswith the fatty acid, which thereby becomes attached to the mineralsurface with its hydrocarbon chain oriented outwards. When enough ofthese oriented hydrocarbon chains become attached to the surface thelatter becomes water-repellant and preferentially wetted by the oil orbitumen. The above method has the disadvantage that the relative amountsof the polyvalent metal salt and the soap are critical, and must becorrectly adjusted for optimum results. Furthermore, two

' solutions must be prepared and applied sepa rately or mixed beforeapplication. Finally, we have found that with many aggregates theefiects obtainable by the above method are less favorable than areobtained with the metalloid halides described herein, either in that theamounts or cost of agent required to obtain adequate coating aregreater, or in that the, degree of coating obtainable with a givenamount of agent is less than with the agents described herein.

We have found that mineral aggregates, particularly of the hydrophilic,siliceous type, can be provided with an. adherent coating of crackedoils or cracked bituminous materials by employing the metalloid halides,preferably the trichlorides of the metalloids of the fifth group of theperiodic system. The use in combination therewith of a polyvalent saltof a heavy metal is unnecessary, arid the careful and exactproportioning of two reagents which must be done when fatty acid soapsare employed is unnecessary. The coatings so obtained are highlyresistant to displacement by water, both immediately or after I themixture has dried. i

While the application to the aggregate of a polyvalent metal salt or theincorporation of such a'salt in the mixture of aggregate, bituminousmaterial and addition agent during the preparation'of said mixture, isnot necessary obtain bituminous material to the mineral aggregate can insome cases be further improved by employing a polyvalent metal salt inaddition to the addition agents described herein. In distinction to theabove use of a polyvalent metal salt with a water-soluble soap of afatty acid, in which use very little or no advantage is obtained unlessthe polyvalentmetal salt is employed in sufficient quantities, the useof polyvalent metal salts with the addition agents described hereinserves principally to supplement or enhance the effects of the additionagents and does not require exact or critical proportioning of 'the saltand addition agent. The amount of polyvalent salt which canadvantageously be used varies from none to 2 moles per mole of additionagent and typically from 0.1 to' 1.0 mole per mole of addition agent. Wehave found that the use of the addition agents described herein in theamounts stated results in an appreciable increase in the viscosity orconsistency of the-bituminous'material, particularly of crackedbituminous materials. This is advantageous in that bituminous materialsof higher consistency have less tendency to be displaced from theaggregate surface by water and are in other respects more desirable, andin that the increase in consistency is obtained withoutthe expense ofprocessing the bituminous materials expressly to obtainhigher viscosityproducts, as by reduction or oxidation.

While we have described our invention as applicable to the coating ofmineral aggregates with bituminous materials with special reference tohighway and/or pavement surfacing, the invention is applicable to thepreparation of products in which a water-resistant bond between mineralsubstances and bituminous material is advanta geous or necessary. Forexample the invention may be adapted for the preparation of bituminousgrouts, mastics, caulking or sealing compounds, enamels, or pipe dips;for the preparation of filled asphalts comprising asphalt and very finemineral fillers, such as are used in composition shingles or roofing; orfor improving the adhesion of siliceous mineral granules toasphaltsurfaced roofing.

Having fully described our invention, it is to be understood that thesame is not to be limited to the details herein set forth, exceptinsofar as the same is defined by the appended claims.

We claim: I

1. The method of forming a water-resistant bond between a siliceousmaterial and a bituminous material comprising incorporating in thebituminous material a small, amount of a halide of a metalloid of thefifth group of the tion of the latter to the siliceous material.

4. The method of forming a water-resistant bond between the siilceousmaterial and the cracked bituminous material comprising adding a smallamount of a phosphorus halide to the said cracked bituminous materialand then applying the same to the siliceous material.

5. The'meth'od described in claim 4 in which i the phosphorus halide isphosphorus trichloride. 6. The method of forming a water-resistant bondbetween the siliceous material and the cracked bituminous materialcomprising adding bond between the siliceous material and the crackedbituminous material comprising adding a small amount of an arsenichalide to the said cracked bituminous material and then applying thesame to the siliceous material.

9. The method described in claim 8 in which the arsenic halide is anarsenic chloride.

10. In the construction of a bituminouspavement in which a crackedbituminous coating material is applied to a mineral aggregate theimprovement.comprising incorporating in the mixture of themineralaggregate and cracked bituminous material a small amount of ahalide of a metalloid of the fifth group of the, periodic system.

11. In the construction of a bituminous pavement in which a crackedbituminous coating material is applied to a mineral aggregate theimprovement comprising incorporating in .the mixture of the mineralaggregate and cracked bituminous material a small amount of a phosphorushalide.

12. In the construction of a bituminous pavement in which a crackedbituminous coating material is applied to a mineral aggregate theimprovement comprising incorporating in the mixture of themineral-aggregate and cracked bituminous material a small amount ofphosphorus trichloride.

13. A coating material for siliceous substances comprising a crackedbituminous material and a small amount of a halide of a metalloid of thefifth group of the periodic system.

13 in which the. metalloid halide is an antimony chloride.

16. A coating material as described in claim 13 in which the metalloidhalide is an arsenic halide.

17. A coating material for siliceous substances comprising a crackedbituminous material and a small amount of a phosphorus halide.

'18. A coating material as described in claim 17 in which the phosphorushalide is phosphorus trichloride. v

ELTON B. TUCKER. HENRY M. GRUBB.

W CERTIFICATE OF CORRECTION Patent No. 2,276,156. March 17, 19l 2.

ELTON B. TUCKER, ET AL.

It is hereby certified thet error appears in the printed specification vof the above numbered patent requiring correction as follows; Page 1,eec- 1 0nd column, line 8-9, for "chloride" read --chlorides; line 11,after "$001 insert -SbBr and that the said Letters Patent should be readwith this correction therein that the some may conform to the record ofthe case in the Patent Office. 7

Signed and sealed this 5th day of May, A. D. 19L 2.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents

